For nearly four decades a combined manual and diary put out by the New York real estate board languished on the shelves of the library set up to preserve the papers of Harry S Truman, US president from 1945 to 1953.

Then an archivist stumbled on the diary pages at the back, and discovered Truman's musings from 1947, the year that marked the beginnings of the cold war and the Marshall plan. The 42 diary entries are his most extensive personal record of that year, said Michael Devine, the director of the library, and the most significant recovery of Truman materials since 1982, when his widow Bess died.

The famously frugal Truman received the blue-jacketed book as a gift in 1946, filling the pages at the back in a neat left-handed script, and making a fair share of spelling and grammatical errors. The first 160 pages are real estate agent listings and adverts, leading the library staff to catalogue it with books from his estate.

Sadly, the irregular entries offer almost no insight into the Truman doctrine to contain the spread of communism in eastern Europe and elsewhere, or the massive infusion of aid after the second world war that became known as the Marshall plan.

It also makes no mention of civil rights, although Truman appointed a commission that year to recommend legislation, and in 1948 desegregated the army.

However the diary does include a rant against Jews, which has surprised scholars because of Truman's reputation for sympathising with them, and his support for the creation of the state of Israel despite the opposition of the state department and members of his cabinet.

On July 21 Truman used the diary to vent his anger at the former treasury secretary, Henry Morgenthau, who had sought his intervention on behalf of a ship of Jewish refugees who had been denied entry by Britain to what was then Palestine.

"He'd no business, whatever to call me," Truman wrote. "The Jews have no sense of proportion nor do they have any judgment on world affairs."

In the same entry Truman goes on to say: "The Jews, I find are very, very selfish. They care not how many Estonians, Latvians, Finns, Poles, Yugoslavs or Greeks get murdered or mistreated as D[isplaced] P[ersons] as long as the Jews get special treatment. Yet when they have power, physical, financial or political neither Hitler nor Stalin has anything on them for cruelty or mistreatment to the underdog. Put an underdog on top and it makes no difference whether his name is Russian, Jewish, Negro, Management, Labor, Mormon, Baptist he goes haywire. I've found very, very few who remember their past condition when prosperity comes."

Although historians said Truman was certainly a product of his era and his upbringing - in a small midwestern town - the remarks did not make him an anti-Semite. "He had a tendency when emotions were running high to put things down on paper," Mr Devine said.

"Truman frequently wrote from the gut and not the head, and there are numerous stories of him asking his secretary whether he had posted a letter so he could pull it out of the outbox."

Robert Farrell, a Truman biographer who edited his private papers, said he detected no deeper hostility in other writings. "I don't think that's the way to interpret that section. He was under intense pressure," he said.

"There is a kind of rhetorical quality to that entry. He was irritated at the moment and as he wrote he sharpened everything. I would not want to assert that this is what he really meant.

"He was turned off by Morgenthau, whom he did not like. What he did think was that Morgenthau was getting into affairs that should not concern him."

Instead, the diary offers insight into the president's capacity for enjoyment - despite the pressures of office, and the petty likes and dislikes that often got in the way.

He wrote of his satisfaction with Marshall as his new secretary of state in January, and the desolation he felt at the death of his mother in July.

Aside from his tirade against the Jews, he used the diary to vent his frustration at the adult children of Franklin D Roosevelt - whom Truman, as vice-president, succeeded on the former's death in office in 1945. "It is a pity a great man has to have progeny! Look at Churchill's," he writes.

The diary offers glimpses of Truman's kindness, and he writes of autographing dollar bills as souvenirs for staff of a house he visited. But the thread running throughout is his candour and optimism.

"Doc tell's me that I have Cardiac Asthma! Ain't that hell. Well it makes no diff[erence,] will go on as before. I've sworn him to secrecy! So What!"